The Works of John Playfair; With a Memoir of the Author ... Volume 5

The Works of John Playfair; With a Memoir of the Author ... Volume 5

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1819 edition. Excerpt: ... valued for their accuracy, such as that of LA CAILLE, containing 515 stars; of BRADLEY, containing 809, Naut. Almanack, 1773; of MAYER, containing containing 998; of MASKELYNE, containing on-ly 36; but the places determined with such ex-actness as to render it extremely valuable. See his-' Astronomical Observations, 1770. BoDE's Atlas, Berlin, ' 1797, is the largestcatalogue, reduced into one body, that has appeared; it contains 17,000. d. The number of the stars, however, visible with the telescope, far exceeds whatever can berec_koned. The bright tract in the heavens, called the Milky Way, seems to owe its white appearance to an incredible multitude of stars, which the eye cannot distinguish. Dr I-lunscnm. has seen 116,060 stars pass through the _field of his telescope in a quarter of an hour; though the field was not more than 15 in diameter. " 32. The most obvious distinction among the stars, is founded on their different magnitudes. Those of the first magnitude, are distinguished by particular names; there are only ten visible in Europe, which all astronomers have a greed to belong to that class. a. The stars visible to the naked eye, are divided, in all, into six classes, not very accurately separated from one another. The ancients counted 15 of the first, 45 of the second, 208 of the third. LA Lanna, 557. HA1-LEYa HALLEY, Phil. Trans. N" 364. Also Vmcn, vol. I. p. 505. b. If 0 be-the class reckoned from the first, 18 X c"is nearly the number of stars in that class. 33. The fixed stars are not scattered over the heavens indiscriminately, but are disposed in groups; to which, from the most remote antiquity, names have been given from certain figures of animals, conceived to be more

Product details

  • Paperback | 122 pages
  • 189 x 246 x 7mm | 231g
  • United States
  • English
  • black & white illustrations
  • 1236738896
  • 9781236738899